The present invention relates to a large-sized flat panel display, and is preferably applied particularly to a plasma display or the like which needs to efficiently radiate heat from a display panel, various boards, and image processing electronic components.
Large-sized flat panel displays such as plasma displays providing high-brightness and high-definition images have been required. This has led to an increase in the number of image processing electronic components and in the quantity of heat generated by a display panel and various boards. Thus, a challenge for the large-sized flat panel display is to cool these heat generating components. As is well-known, to cope with the increase in the quantity of heat generated by the display panel and the various boards, an exhausting cooling fan is obliquely installed on a ceiling portion of a rear cover to discharge exhaust heat from the display panel module and various boards for cooling. This configuration is described in, for example, JP-A-2005-235843.
Furthermore, as is well-known, the cooling fan is installed between the display panel module and a non-display-surface-side cover so as to allow cooling air to flow upward in a vertical direction. This configuration is described in, for example, JP-A-11-237844.
For the configuration described in JP-A-2005-235843, enough consideration is not made for the temperature distribution of the display panel module, the temperature distribution of air inside a housing, and propagation of noise from the cooling fan. In particular, in this configuration, cooling air sucked into the housing through an opening formed on a lower side of the housing is allowed to flow upward by the action of buoyancy caused by natural convention and by the cooling fan, installed on the ceiling surface of the rear cover. Thus, the temperature distribution of the air inside the housing is formed such that the temperature increases consistently with the height in the housing. Accordingly, the temperature distribution for the display panel module is formed such that the temperature is higher on an upper side of the display panel module and lower on the lower side thereof. The temperature may differ between a top surface and a bottom surface of the display panel module by at least 10° C. In general, the lifetime of the display panel depends on the temperature of an uppermost portion thereof. Thus, when the flow rate of the cooling fan is increased to decrease a temperature of the top surface of the display panel module, the temperature margin of the lower side of the display panel module is wastefully increased. Furthermore, fan noise increases.
On the other hand, the brightness and definition of images provided by image displays have been improved year by year. The resulting tendency is an increase in the number of required image processing electronic components and in the quantity of heat generated by the display panel and a display driving board and the like. In particular, in recent years, a plurality of image processing electronic components may be arranged at an upper end of the display panel module to deal with the increased definition. Heating of the housing thus progresses gradually from the lower side thereof. Consequently, the heated air inside the housing is positioned in the upper part thereof, where the air is likely to be built up. Thus, the configuration in JP-A-2005-235843 provides insufficient heat radiation, possibly causing the temperature of the components to exceed an upper limit value. Moreover, part of the cooling air flowing in from the lower part of the housing or the like may be exhausted to the exterior of the housing by the cooling fan, with the temperature of the cooling air not significantly increased. This may disadvantageously prevent promotion of the heat radiation from the display panel module. Furthermore, an outlet of the cooling fan directly faces the exterior of the housing. Thus, the noise from the fan is likely to propagate to the exterior, preventing an increase in fan noise being inhibited.
Moreover, in the configuration described in JP-A-11-237844, the cooling fan is installed between the display panel module and the non-display-surface-side cover. In some commercially available products, the cooling fan is installed, for example, below a power supply board in a similar direction so as to improve cooling effects. However, for plasma displays and the like, on which a strong requirement for a thickness reduction is placed, a large-sized fan cannot be installed in the housing owing to a restriction on the depth dimension of the housing. This makes it difficult to increase the flow rate of the cooling fan above a currently achieved value to promote the cooling of the components, without increasing the fan noise.